Conventionally, an optical adapter provided with a port having opposite ends into which optical connectors are to be inserted, respectively, has been used as an interface component for connecting the optical connectors within an optical transmission device. In the optical adapter, it is assumed that when the optical connector is pulled out of one end of the port, light emitted from an optical connector inserted into the other end of the port is leaked to the outside. The leakage of the light emitted from the optical adapter hinders the safety of a user of the optical adapter.
Thus, as a measure to avoid the leakage of the emitted light, an optical adapter provided with a shutter part which is opened/closed with the insertion/the pulling out of an optical connector, at one end or each of opposite ends of the optical adapter has been developed. In the optical adapter, when an optical connector is inserted into one end of the port, the shutter part leans back to a retreat position that does not block light emitted from an optical connector inserted into the other end of the port. Then, when the optical connector is pulled out of the one end of the port, the shutter part is raised up to a blocking position that blocks the emitted light, from the retreat position and reflects the blocked emitted light onto a predetermined surface of the housing of the optical adapter. Accordingly, the leakage of the light emitted from the optical adapter when the optical connector is pulled out is avoided.
However, in recent, a multi-port type optical adapter having a plurality of ports inside one housing has been developed with the implementation of high density within an optical transmission device. When the shutter part is applied to the multi-port type optical adapter, it is assumed that the shutter part is installed at one end or each of opposite ends of each port.
FIG. 19 is a view illustrating an exemplary configuration of a multi-port type optical adapter. The multi-port type optical adapter 100 illustrated in FIG. 19 includes a plurality of ports 120 (ports 120-1 to 120-4) provided in parallel with each other inside a housing 110. Hereinafter, the ports 120-1 to 120-4 may be collectively referred to as ports 120 when the ports 120-1 to 120-4 are not required to be discriminated from each other. Likewise, the other components such as shutter parts 130-1 to 130-4 may also be collectively referred to. The shutter parts 130 are provided at one-side ends of the ports 120, respectively. Optical connectors 140 are inserted into the other-side ends of the ports 120, respectively. In this state, when the optical connectors 140 are pulled out of the one-side ends of the ports 120, the shutter parts 130 are raised up to the blocking position that blocks the light emitted from the optical connectors 140, from the retreat position. Then, the shutter parts 130 reflect the blocked emitted light onto the common surface of the housing 110 among all the ports 120-1 to 120-4, i.e., the bottom surface 110 of the housing 110.
However, when the emitted light reflected from all the shutter parts 130 is directed toward the bottom surface 110a of the housing 110, only the bottom surface 110a is intensively heated by the irradiation of the emitted light, and hence, the optical adapter 100 itself generates heat.
As described above, in the multi-port type optical adapter, when the shutter parts entirely reflect the emitted light to the common surface of the housing among the ports, the heating value of the optical adapter increases. Recently, there has been the tendency that the number of ports in the multi-port type optical adapter gradually increases, and the heating value of the optical adapter may gradually increase with the increase of the number of ports. When the heating value of the optical adapter increases, the housing of the optical adapter may be melted.
The following is a reference document.    [Document 1] Japanese Laid-Open Patent Publication No. 2004-94109.